1. Field of the Invention
This invention relates to a process for tuft and filament binding in unfinished carpet using hotmelts based on amorphous poly-α-olefins and bonded materials produced by the process.
2. Discussion of the Background
Pile threads and pile loops of unfinished carpet have hitherto been typically attached using carboxylated SBR latex filled with different amounts of chalk. In this process, the water has to be evaporated from the latex after application. This takes place, at appreciable expense in terms of time and energy, in drying ducts up to 40 m in length. An additional operation is then necessary to apply a further coat to the backside of the carpet. This can be for example a bituminous composition, a polyurethane foam or, as described in EP-A-0 309 674, a heavy-duty coating composition. Carpets of this kind, wherein tuft and filament bonding is effected by means of the abovementioned latices, however, are difficult to recycle.
DE-A-26 10 141 discloses tufted carpets where the backing material is given a subfacial coating of an atactic poly-α-olefin before use. The punching through of the pile yarn is followed by a hot fixing step. Owing to resistance due to the coating, however, the pile yarn is difficult to punch through, and there is also a risk that coating residues will adhere to the needle and interfere with its ability to punch through the backing. Moreover, this technique only allows for tuft bonding and not for single filament bonding. For these reasons, the process has not been implemented to date.
DE-A-19 59 141 discloses a carpet backsized with a composition comprising ethylene copolymer, wax and appreciable amounts of a resin mixture. However, the ethylene-vinyl acetate copolymer which is primarily used in this reference leads to appreciable odor problems during use. The resins used are costly; furthermore, the composition has a very low softening point and hence a very low heat resistance. The same is true of the composition described in GB 1 155 786.
EP-A-0 518 014 discloses three-dimensionally formable, recyclable floor carpets having a backcoating containing a poly-α-olefin. However, the backcoating contains appreciable amounts of isotactic polypropylene and filler and therefore is very viscous in the molten state. The backcoating is applied in a sufficiently thick layer for the floor carpet to be permanently three-dimensionally formed, but it has been determined that such a coating composition does not provide tuft and filament bonding.